The present invention generally relates to pedal actuated hydraulically devices found in motor vehicles, and more particularly, to a hydraulic brake system, including a a brake pedal assembly, that is collapsible from an operative condition upon imposition of a deceleration to the motor vehicle.
It is generally known in the automotive vehicle design arts that it is desirable to configure components arranged within the passenger compartment of the vehicle to reduce adverse effects on the vehicle occupants when during a collision. For instance, many vehicle interior components are designed to absorb energy or minimize forces transferred to occupants during a collision impact, thereby mitigating injuries. Brake pedal assemblies, too, may transfer collision induced forces to a driver""s leg. This is because in a severe frontal collision, deformation of the vehicle dash panel can cause the brake pedal assembly to move rearward toward the driver""s leg. In addition, the momentum of the driver during the collision can force the driver""s leg into the brake pedal assembly.
Conventional vehicle brake pedal assemblies, generally have a foot pedal pad connected to a lever and a piston push rod, which, with assist from a vacuum booster, compresses a master cylinder, which in turn generates hydraulic fluid pressure. One approach to minimizing the energy transferred to a driver""s leg through a brake pedal assembly includes causing a failure in the structure supporting at the pivot point of the pedal assembly, thus allowing the pedals to move freely with little constraint following a severe frontal collision. Another approach includes triggering a valve mechanism that opens the hydraulic system, resulting in a substantial reduction of the hydraulic pressure in the system, thereby allowing the pedal to completely collapse. This and other similar approaches significantly increase the cost and complexity of pedal actuated systems. Additionally, they are generally designed to render the brakes inoperative following an initial vehicle collision.
Accordingly, there exists a need, heretofore unfulfilled, for a cost efficient device for use in a vehicle, capable of collapsing a brake pedal assembly to reduce the energy transferred to a driver""s leg without compromising the braking capabilities of the vehicle both during and after the initial collision.
In accordance with the teachings of the present invention, a brake fluid pressure relief apparatus, for use with a brake pedal assembly in a motor vehicle is provided which reduces energy transmitted to a driver""s leg from the brake pedal system during a vehicle collision, while retaining the ability to control and maintain vehicle braking. The brake fluid pressure relief apparatus includes a first valve having an inlet in fluid communication with an actuator assembly. The first valve is operated by an inertial mass, allowing passage of hydraulic brake fluid from the inlet through an outlet when the inertial mass reaches a deceleration in excess of a predetermined deceleration limit. The brake fluid pressure relief apparatus further includes a second valve in fluid communication with the outlet of the first valve. This second valve is opens to allow passage of the hydraulic brake fluid into a reservoir when the pressure of the hydraulic brake fluid exceeds a predetermined pressure limit.
These and other features, advantages and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims and appended drawings.